Male adolescent (~15.8 yr) swimmers (N = 15), who had trained for at least 12 hours per week for two years, were compared to a non-training group (N = 8) with similar anthropometric dimensions.

Swimmers showed a significantly greater left ventricular diastolic internal diameter, interventricular septum, and left ventricular posterior wall when compared to non-trainers. Left ventricular mass and deceleration time were increased in swimmers. Systolic, diastolic, and global heart functions were similar between groups.